Biplane videoangiocardiograms
of the left ventricle are stored on a video-disc recorder and replayed onto a TV monitor in a stop-action mode. The ventricular contours are successively traced with a light pen and stored on a scan converter (TEKTRONIX 4501) by means of a specially designed sweep-stop unblanc unit. The scan converter reads out the stored information automatically. During each horizontal scan, up to four counters are triggered by the heart boundary pulses. Information corresponding to each line of the contour which is stored in the buffer is read into a Control Data 1700 computer by means of a coding and counting unit in real time and stored in an array. Playback of the stored information onto a storage scope allows a visual check of the circumscribed image. The computer utilizing both images calculates the cross-section area obtained from each line pair of video-information by an elliptical fit. A three-dimensional summation of all volume slices together with the appropriate calibration factors results in a computer displayed volume. Programs are available which allow a simultaneous or successive evaluation of the biplane video-information with the additional possibility to correct different amplifications of the heart in both planes by a "blow up" procedure in the latter program.